Tasker, a task runner
Tasker is a task runner, plain and simple. Define tasks, schedule them, and that's it !
Give it a try ! Just create the following
version: "2" services: tasker: image: strm/tasker volumes: - "/var/run/docker.sock:/var/run/docker.sock" environment: configuration: | schedule: - every: minute task: hello tasks: docker: - name: hello image: debian:jessie script: - echo Hello world from Tasker
And that's it, now you have a task, running inside docker every minute, using the
debian:jessie image (and bash inside this image), to run the script defined inside
Configuration is segmented, the concept is, you first configure your tasks, and then you configure what will activate them. Then just map your configuration file to
/application.yml in the container, or if you run it outside docker, map it to a file called
application.yml in the same folder that you are running the application from.
Here is an example with several constructions:
config: global-environment: - http_proxy="http://yourproxy:8080" schedules: - every: 5 minutes task: test - every: Saturday task: backup - cron: 0 0 13 * * * task: test tasks: docker: - name: backup image: debian:jessie script-strict: true script: - echo Running the backup environment: - TEST=environment variable value volumes: - someVolume:/whatWouldBeMappedInTheContainer
At this moment there is only one kind of task,
docker tasks. Those tasks ran inside docker containers, plain and simple as that. More task executers will be implemented in a near future, watch this repository to be sure you get the updates !
image- the image in the very same format as it is expressed for docker, in
repo/image:tagfor images in the default repository, of
server/repo/image:tagfor images residing somewhere else.
environment- Define environment varibales to be used in the task execution, they follow the same pattern that you use in
docker-compose.ymlfile, a list of
volumes- An array, just like you map
ports- An array, just like you map
network- If you wish to attach or use any other network that you have. If the desired network doesn't exist, it will be created.
Configurations regarding container life cicle:
keepContainerAfterExecution- Keep container after it executes, won't delete it, WARNING it can leave a lot of trash. USE IT FOR DEBUGING ONLY !
always-pull- A boolean (true/false) property, when it's true, Tasker will pull a newer image version updating it if there is a newer one available.
reuse-container- A boolean (true/false) property, if the container doesn't exist, create it, if there is already a container with that name, reuse the container.
Entrypoint and Arguments
You can pass parameters to your task and set the entrypoint of the image as you pass in docker command line. Example:
tasks: docker: - name: hello image: debian:jessie entrypoint: /bin/bash arguments: -c,echo Aloha world
The example above execute
/bin/bash passing as argument
-c echo Aloha world. Comma can be used to separate arguments in an inline array. It uses a YML structure, so you can rewrite it as you wish. For example, you can declare the parameter array as a list:
tasks: docker: - name: hello image: debian:jessie entrypoint: /bin/bash arguments: - -c - echo green bar
Both examples will produce the very same result.
script directive is a facilitator to setting the
/bin/sh and pass as arguments as a list of commands. It's syntax is just a list of commands like:
- name: helloScriptStrict image: debian:jessie script: - echo Hello from Docker
Commands will be executed sequentially, no matter the result. To enable the strict mode, where the next command will only be executed if the previous command was successful (exit status 0), you can use the
script-strict property. For example
- name: helloScriptStrict image: debian:jessie script-strict: true script: - echo This is the first line - echo This second line will only be executed if the above command properly runs
Docker images and pulls
Tasker uses the concept of lazy loading, in other words, it will pull your image when it will run at the very first time. You can use
always-pull=true in your docker task definition if you want to keep updating the local image everytime your task runs.
Other considerations about docker tasks
- Tasker can run in a swarm or single instance, but it will schedule tasks to run in the current node.
- You can set
DOCKER_HOSTenvironment variable to this image, to make it run the scheduled tasks in a remote docker host.
secretsaren't available at the moment
Scheduler configuration is an important aspect in Tasker. The scheduler is responsible to what it's name suggests, schedule tasks to be executed. It is defined in
schedule section of the configuration file. Example
schedule: - every: 10 minutes task: test - cron: 00 00 11 * * * task: test
schedule is an array of schedules. There are two ways to schedule an task. One is by giving it an interval using
every property or
cron. You can name a schedule with the
name attribute, but it isn't mandatory, you can have anonymous schedules if you prefer.
Every is a representation for a more simple understanding, like
every: minute, is far more readable, but won't give you the same power as the
cron directive. The
every parameters can be:
- Minute - Every minute inside one hour period. For example,
every: 10 minutes, will result in 6 executions, at 00, 10, 20, 30, 40 and 50. Every minute scheduled task will start it's first execution at the first minute of the hour (00).
- Hour - Every hour inside one day period. For example,
every: 6 hourswill result in 4 executions, at 00, 06, 12 and 18. Every hour scheduled task will start it's execution at the very first hour of the day (00 - midnight).
- Weekday - Every weekday as in the list (Monday, Tuesday, Wednesday, Thursday, Friday, Saturday and Sunday). The task will be executed at the first minute of the first hour of the respective day. For example
- Year - Will be executed in the very first second, of the first minute, of the first day, of the first month of the year.
cron is another way to set the expected trigger to your scheduled task. It obey the standard
unix cron format, but with the exception that it has one more field. Is a field representing
seconds, and is the first field, from
59 are the accepted values.
Is possible to configure Tasker to notify other components when tasks finish. Notifications are triggered after the task is completed. Notifications are defined in the
notify section of the configuration file, separated for each sub-type of notification, for example:
notify: email: - name: notifyEmailTest task: helloNotifyEmail when: always server: mail.gmail.com subject: Email subject sender: firstname.lastname@example.org content: Your message
Notifications need to be linked to a task, so a valid
task should be informed.
name- A name to identify the notification.
task- Which task will trigger this notification
when- When the trigger will run. There are three scenarios,
always- Is the default behavior, it will trigger the notification every time that the task runs.
on-success- Will trigger the notification only if the task is successful.
on-error- Will trigger the notification only if the task isn't successful.
In Tasker, e-mail notifications are a sub-category of notifications. E-mail notifications are configured with
email: field, inside the
notify section. Bellow a simple example configuration using Gmail:
notify: email: - name: notifyEmailTest task: helloNotifyEmail server: smtp.gmail.com username: email@example.com password: yourpassword recipients: firstname.lastname@example.org subject: Email subject content: Your message
A complete example bellow
notify: email: - name: notifyMyTaskOnErrorOnly task: yourTaskName when: on-error server: localhost port: 3025 username: email@example.com password: yourUserPassword protocol: smtp starttls: true debug: true subject: Email subject recipients: - firstname.lastname@example.org - email@example.com content: | Multiline Task finished
Configuration parameters regarding the connection to the e-mail server:
server- Remote server where the email server is running. Default
port- Remote port where the server is listening to. Default
username- Username that will be used in the authentication with the server.
password- Password for the given username.
protocol- Protocol to use for e-mail transfer. Default
starttls- Use TLS or not. Default is
debug- Enable a more verbose output of the e-mail transfer process, use it only for troubleshooting. Default
validate-server-on-configuration-load- Validate the e-mail configuration when Tasker startup, and abort it if isn't possible to connect to the e-mail server. Default
Configuration parameters regarding the e-mail to be sent:
subject- The subject of the e-mail.
FROMfield in the e-mail.
recipients- A list of e-mail addresses that will receive the e-mail.
content- The content of the e-mail.
template- A velocity template that will be rendered and will generate the
contentof the message.
If you wish to use the
template property, you need to follow Velocity Template Language specification.
There are some variables that can be accessed in the context of the execution of the template, and those are:
success- (Boolean) Will be
trueif the task was successful.
error- (Boolean) Will be
trueif the task wasn't successful.
log- (String) The output of the execution of the task.
task- (String) The name of the executed task.
start- (Date) The Java Date when the task started.
end- (Date) The Java Date when the task finished.
If you want to suppress some of the logging information, you can add the following to your configuration
logging: level: ROOT: WARN org.springframework.web: WARN
config aka Configuration of the Configuration section
Configuration is the place where additional components of Tasker can be configured.
global-environment- A list of environment variables that will be assigned to all tasks. Note that this variables are overwritten by
environmentvariables section of each task in case of a conflict.